Embedded optic fiber page

ABSTRACT

A page fabricated with embedded optical fibers is used as an input/output device to facilitate man-machine communication. Pinhole-size perforations in the surface of the page serving as entry/exit ports are located above ends of the embedded optical fibers, thereby to expose the ends of the fibers to the top surface of the page, with the fibers being routed beneath the surface of the page to exit points at the edge of the page. As an input device, information is entered by marking the page with a pencil such that pencil lead is deposited in a selected perforation to prevent light from passing through the perforation in the page and into the underlying optical fiber, the state of the fiber being detected and converted into one bit of information. The user&#39;s actions in marking the page may be guided by pictures and words printed on the page, which may be made of paper. As an output device, selected optical fibers are driven with a light source which results in a display of information by light emanating from the perforations at the ends of the driven fibers. In a further embodiment, a light path is established by a fiber embedded in the page, in which the fiber is separated along its length at a point under a perforation, with occluding material deposited through the perforation for blocking transmission of light through the fiber. In another embodiment a matrix of fibers is embedded in a page, with connections of a row and a column at a crossover point being provided by a coupling fiber spliced therebetween, the coupling fiber being separated under a perforation in the paper through which occlusive material may be deposited to selectively block the optical coupling between the row and column. In a still further embodiment, the embedded fiber optic page may be used with either light-detecting or light-emitting pens.

FIELD OF INVENTION

This invention relates to a method and apparatus for man-machineinformation transfer and more particularly, to an embedded optic fiberpage operative as an input or output device.

BACKGROUND OF THE INVENTION

It has long been recognized that full utilization of computers requiresconvenient devices for man-machine communication. Among such devices aremanual keyboards, computer graphics terminals, and voice-recognitionsystems. By contrast, the most widespread medium for communicationbetween man and man, apart from speech, is the printed page. It has beena goal, ever since the development of the digital computer, to provideconvenient man-machine interfaces such that the conveying of informationto and from a computer is effected with minimum expense, training time,and distraction to the user thereby to establish greater utilization ofthe computing power afforded by digital computers. In the past, keyboardactuated systems have been utilized as input devices, as well as suchdevices as punched cards, optical readers, and graphics tablets.

It will be appreciated that the above mentioned input devices involveauxiliary equipment which can be costly or bulky. Moreover, withkeyboard-oriented devices, entry of information frequently is based on aformal man-machine dialogue which may impose obtrusive or annoyingmental steps upon the user. Note that mental manipulations required forthe entry of information in this manner are somewhat removed from thenormal way in which human beings communicate via the written word. Inaddition, keyboard entry requires a certain amount of typing skill. Thedisadvantages of graphical input devices include the cost of thehardware and lack of easy portability.

In another class of input/output (I/O) devices, fiber optics have beenutilized in the past to provide a coding system for the entry ofinformation into a computer. For instance, fiber optics have beenutilized as illustrated in U.S. Pat. No. 3,612,888 for reading a punchedcard containing information. In this patent, the optical fibers are usednot only to detect the presence or absence of light coming through thecard at a particular location, but are also utilized to establish apredetermined code by virtue of the routing of the optical fibers.

Moreover, encoding has been accomplished by embedding fiber opticelements in a card such as illustrated in U.S. Pat. No. 3,728,521. Inthis patent, fibers exposed to the edges of the card are individuallyilluminated by light sources. Coding for the card is accomplished byinternally severing a predetermined fiber and by providing occludingmaterial at the severed point, thereby to prevent light from travelingfrom one end of the fiber to another. The non-illuminated ends of thefibers are provided with detectors so as to permit decoding of the stateof the fiber optic transmission path.

One of the problems with the encoded card described in U.S. Pat. No.3,728,521 is that the encoding is accomplished prior to final laminationof the fibers into the card. The coding is therefore fixed at the timeof manufacture and is not readily alterable by a user either to changethe code or to enter information other than that which was originallyencoded. Thus, while fiber-optic coded cards have been utilized in thepast as input devices, the coding has been fixed or at least not readilyalterable by the user. This is also true, for instance, with respect tofiber optic coded keys which are precoded and utilized in the manner ofa traditional key.

SUMMARY OF THE INVENTION

An exceptionally simple, portable means for man-machine input/output isprovided by a page fabricated with embedded optical fibers, the ends ofwhich are exposed beneath small apertures in the top surface of thepage. These apertures serve as entry or exit ports for information inputor display. Specifically, information input is accomplished by occludingor marking of the apertures by the user. Such marks result in theblocking of optical paths through the embedded fibers. The presence orabsence of light in a particular path is then detected electronically.Thus, one bit of information is provided opto-electronically, in directcorrespondence with the presence or absence of a mark applied to thepage.

Information output is accomplished by utilizing electronically drivenlight sources. Because ends of the fibers are exposed through aperturesin the page, light can be made to exit an aperture by driving a sourceat the non-embedded end of a fiber. In the case of both input andoutput, the presence of printed text or pictures adjacent the aperturescan be utilized to establish context and meaning in a way that isnatural to the user. Not only is a convenient information input/outputdevice provided, but also the margin for error in the entry ofinformation is minimized, due to the juxtaposition of the entry/exitport with information which enables the individual to decide whether ornot to select the entry/exit port. The subject input/output devicereduces the number of functions an individual must perform to enterinformation, in that no typing skills or complicated mentalmanipulations are necessary. Thus, the subject input/output deviceprovides an unobtrusive, natural interface for communicating with acomputer.

In summary, the embedded fiber page acts as an information transducer ortransduction device in which the informational state of an embeddedfiber may be selected or detected depending on the intended mode ofoperation.

In one embodiment, man-machine communication is provided by applying amark with a pencil or a similar instrument to the page at a particularentry/exit port which mark blocks the entry of ambient light to thefiber. Whether or not a fiber is transmitting light can beconventionally detected and decoded so as to provide input to aninformation processor. While this system utilizes ambient light, thesame type of man-machine interface may be provided through theutilization of a non-ambient or "active" system-driven light source.

In an active system, a light source is positioned at one end of a fiberand a light detector at its other end, and the fiber is separated at apoint under an entry/exit port so that adjacent fiber ends are inspaced-apart axial alignment. Occluding material is then selectivelyapplied at the port so that the material is deposited in the areabetween the separated end of the fiber. Without occluding material thereis sufficient transmission of light from one severed end to an adjacentsevered end of a fiber to provide an uninterrupted light path, whereasthe provision of the occluding material between the spaced adjacent endsinterrupts the light path.

Alternatively, an active system may be provided by aligning two fibersside by side, driving one fiber with light from a light source, andproviding the other with a detector. Both fibers terminate at the sameentry/exit port, and light transmission is accomplished by backscattering and reflection from the walls of the entry/exit port.

All of these embodiments are to be distinguished from the devicedescribed in the aforementioned U.S. Pat. No. 3,728,521 in that in thesubject system, the entry/exit ports are available at the surface of thepage, which permits encoding by one other than the manufacturer.

The subject input/output device can take on many convenient forms. Itmay be used as a catalog sheet so that catalog ordering may be simplyaccomplished by marking the catalog sheet adjacent the description ofthe item ordered. Each page of the catalog may be connected by anoptical fiber coupling link to a decoding unit which is in turn coupledto a modulator/demodulator (modem). The modem connects the user directlyto the manufacturer's computer by a telephone link. Thus, the personentering orders merely marks the catalog sheets anywhere it isconvenient to do so, with ordering being accomplished by plugging thesheets into a decoder/modem unit.

The subject input/output device may also be utilized in a game format inwhich answers to game questions are transmitted optically to a decoder.The system may be arranged such that a decoded answer results in thedriving of selected fibers to indicate to the user whether or not theresponse was acceptable in the game format. Such games include the socalled "scratch and win" lottery games in which preprinted occlusivematerial is removed from the surface of a game card by scratching.

The fiber optic embedded paper may, of course, be utilized foreducational or training material, or indeed for any type of input to acomputerized system. User responses can also take the form of drawingrather than button-pushing or knob-twirling. Moreover, the stimuluspresented to the user can consist of clear, full-color pictorialmaterial. Computer feedback can be provided in a dynamic, graphic mannervia light-output display.

The subject device can be employed in office automation. For example,responses to office memoranda can be generated via the annotation of apage by a reader. These responses can be electronically collected,avoiding the time delays and errors of mailing and sorting.

Up to this point, the coding of single optical paths has been describedin terms of a convenient system of selectively blocking light in thefiber optic light path. In order to reduce the total number of fibersneeded for a given number of apertures, an orthogonal matrix of fibersmay be embedded in a paper, in which the coupling between apredetermined row and a predetermined column is provided by an opticalcoupling fiber spliced between the two at a crossover point. Eachcoupling fiber is separated intermediate its ends under an entry/exitport. The splice may either be made light conductive or non-conductivedepending upon the absence or presence of occluding material depositedthrough the entry/exit port which overlies the separation provided inthe coupling fiber. Thus, information is specified through theselectable occluding of linkages between rows and columns. Therow/column location of the occluding material may be decoded from thematrix by conventional strobing or addressing techniques.

It is therefore a feature of the subject invention to transduce visiblemarkings upon paper into electronically manipulatable informationwithout the use of conventional optical character recognition hardware.The paper itself serves as the primary information transducer by meansof the optical fibers embedded in the page. Moreover, in a two-waysystem, appropriately driven light sources may provide the user with adisplay of information at the page.

It will be appreciated that three functions are carried out in order tomechanize the transduction process. First, the input function isrealized by marks applied to a page with a pencil or similar instrument.Second, optical signal information regarding the presence and locationof marks is produced by a resultant blocking of light within opticalfibers embedded on the page. Finally, optical-to-electronic signaltransduction is produced by photodetectors associated with the fibers,with the state of the photodetector outputs unambiguously characterizingthe presence and location of marks on the page.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features of the subject invention will be betterunderstood in connection with the detailed description taken inconjunction with the following drawings, of which:

FIG. 1 is a block diagram illustrating the utilization of an embeddedfiber page having surface entry/exit ports with processing apparatus;

FIG. 2 is a cross-sectional diagram illustrating ambient light enteringa surface entry/exit port provided in a page having an embedded opticalfiber;

FIG. 3 is a cross-sectional diagram illustrating the depositing ofocclusive material into an entry/exit port aperture by means of apencil;

FIG. 4 is a diagramatic illustration of an optical fiber illustratingits acceptance cone;

FIG. 5 is a cross-sectional diagram illustrating the page of FIG. 2provided with a light transmissive layer which permits the provision ofocclusive material immediately above the surface entry/exit port,thereby to provide eraseability for the subject system;

FIGS. 6A and 6B are cross-sectional diagrams illustrating the provisionof a page provided with an optical fiber separated along its lengthunder a surface entry/exit port;

FIGS. 7A, 7B, and 7C are diagramatic illustrations of the utilization ofthe subject invention as a catalog sheet, as a game card, and a page ina book respectively;

FIG. 8 is a diagramatic illustration of one embodiment in which eachfiber has associated with it one entry/exit port;

FIG. 9 is a diagramatic illustration of the utilization of a serpentinedfiber embedded in a sheet to which is coupled individual optical fibersassociated one each with an entry/exit port;

FIG. 10 is a diagramatic illustration of one method for splicing opticalfibers together;

FIG. 11 is a diagramatic illustration of a matrix arrangement of fibers,illustrating the utilization of a selectably occludable coupling fiber;

FIG. 12 is a diagramatic illustration of the utilization of a singleoptical fiber with an interruptable portion adjacent an entry/exit port;

FIG. 13 is a diagramatic illustration describing optical transmissionacross a separation in a fiber in terms of the diameter of the opticalfiber and spacing between fiber ends;

FIG. 14 is a graph illustrating the loss of light intensity from onefiber section to another in terms of the dimensions illustrated in FIG.13;

FIG. 15 is a cross-sectional and diagramatic illustration of one type offiber optic connector which may be utilized to couple the embeddedoptical fibers to processing equipment;

FIG. 16 is a diagramatic illustration of the connector of FIG. 15 shownpositionable at the edge of an embedded fiber paper, in which theembedded fiber paper is provided with a reinforcing strip andpositioning detents;

FIG. 17 is a block and diagramatic illustration of the subjectinput/output device used with a light-detecting pen; and,

FIG. 18 is a block and diagramatic illustration of the subjectinput/output device used with a light-emitting pen.

DETAILED DESCRIPTION

A system utilizing the subject input/output device is illustrated inFIG. 1 in which an embedded fiber paper 10 having surface entry/exitports 12, is interposed between a light source 14 and a detector array16. In one embodiment, entry/exit ports 12 are in the form of pinholesize apertures in the top surface 13 of the paper, and, as will bedescribed, each overlies an end of an embedded optical fiber, the otherend of which is led through the paper to the edge of the paper orbeyond. Depending on the mode of operation, light source 14 either mayilluminate the entire page as would be the case with ambient light, or,in the case of the device being utilized as an output or display device,may include an array of light sources associated one each with anembedded fiber. The detector array in general includes a number ofdetectors associated one each with an optical fiber. The output ofdetector array 16 is coupled to a timing/decoding unit 18 which is inturn coupled to a processing unit 20. In the embodiment illustrated,manual input is provided through the utilization of a pencil 21 which isused to mark directly on the paper in selected locations, thereby toencode paper 10.

The ports designated as entry ports for the paper are surrounded bycircles 22, with entry ports 12 located at the centers of the circles.In one embodiment, the entry ports are no bigger than a pinhole,although the size may vary depending on the marking device or fiberutilized. As described hereinbefore, the depositing of graphite orpencil lead into an aperture or perforation forming entry port 12,blocks light from entering an underlying fiber. The mark determines theoptical state of the underlying fiber, i.e. conducting light or not,which is subsequently sensed by a detector in detector array 16. Inorder to scan or address a given detector, timing and decoding signalsfrom timing and decoding unit 18 are applied over line 19 to detectorarray 16, such that the presence or absence of marks at the individualentry ports may be ascertained. The output of timing/decoding unit 18may be further processed at a processing unit 20 so that informationmanually entered by marking paper 10 may be utilized.

Alternatively, signals from processing unit 20 may be coupled as overdotted line 30 to the timing/decoding unit. Signals decoded at unit 18are coupled over line 31 to activate the aforementioned array of lightsources for driving selected fibers within page 10. By way ofillustration, this results in a display of the word "YES" as indicatedat 32. When light source 14 is driven so as to illuminate selectedfibers, the associated apertures or perforations act as exit ports andemit light, the pattern of which provides the display.

Thus, the embedded fiber paper acts in two modes, the first being as aninput device, and the second as an output device. In the first mode,light source 14 serves to illuminate the ends of fibers within the paperor page, with the encoding being provided by the blackening of aselected circle or circles. In the second of the above described modes,light source 14 takes on the form of an array of light sources, withselected light sources being utilized to drive selected fibers, therebyto provide the display.

Moreover, it is possible to provide a matrix of fibers for the purposeof reducing the number of fibers required for a given number ofentry/exit ports. As will be described, the matrix may be scanned inraster scan fashion, with the sensing of a crossover point beingaccomplished by activating the detector at a selected row when aselected column is driven with the light source.

Ambient Light Systems

Referring now to FIG. 2, the subject input/output device may be in theform of a laminated paper, which in one embodiment includes a top layer40 and a bottom layer 42, in between which is sandwiched an opticalfiber 44. While the subject invention will be described in terms ofoverlying paper layers, it will be understood that the laminationmaterials may be of any suitable type. Also, apertures may be made onboth surfaces of the page. The laminar structure of FIG. 2 is providedwith an entry/exit port in the form of an aperture or hole 46 throughthe top surface 48 of the laminar structure, which aperture extendsdownwardly until it clears the face or end 50 of optical fiber 44.

In operation, light enters aperture 46 as illustrated by line 52.Thereafter, the light either directly enters end 50 of optical fiber 44,or is reflected as illustrated at 54 and 56 by the interior walls of theaperture and then enters end 50.

In one embodiment, the optical fiber is four mils in diameter, and thethickness of each paper layer is four mils. The paper layers or sheetsmay be adhered to each other in a conventional manner with adhesive.Assuming the use of pressure sensitive adhesive, when the optical fibersare to be sandwiched between two sheets, all that is necessary is to layout the fibers on the sheet containing the pressure sensitive adhesiveand then place a cover sheet such as sheet 40 over the structure.Thereafter, apertures may be provided at selected locations at the endof predetermined optical fibers.

Referring now to FIG. 3, when it is desired to prevent light fromentering end 50 of optical fiber 44, occlusive material 58 is depositedin aperture 46. In one embodiment, the occlusive material may be pencillead or graphite, with the depositing of graphite being accomplished bythe marking of the aperture with tip 60 of a conventional pencil.

Referring now to FIG. 4, the acceptance cone 62 of fiber 44 isillustrated as being relatively narrow, generally on the order of 30°,resulting in a half angle of 15°. In the configuration of FIGS. 2 and 3,only one half of the acceptance cone is utilized since light enters thefiber only from the region above the fiber end. Although an opticalfiber has a limited acceptance cone, light is able to enter this coneboth because of non-normal rays entering the aperture, and because ofscattering within the aperture itself.

Referring now to FIG. 5, when eraseability is required, a transparentlayer 64 is positioned over layer 40, with a mark 66 of occlusivematerial preventing light from entering aperture 46. In the embodimentillustrated, mark 66 is provided by tip 60 of a conventional pencil. Theuse of a transparent cover sheet allows printed material on layer 40 tobe viewed through layer 64.

Thus, FIGS. 2 through 5 illustrate a passive ambient light embodiment ofthe subject invention in which encoding of the paper is accomplished bythe deposition of occlusive material at or adjacent the end of anoptical fiber embedded in the laminar structure illustrated.

Active Systems

Use of active light sources such as light emitting diodes (LED's) ratherthan ambient light can simplify the task of signal detection byenhancing the signal-to-noise ratio. In order to provide an activesystem so as to improve the signal-to-noise ratio, as illustrated inFIG. 6A an optical fiber 70 is sandwiched between two layers 72 and 74,and is separated at a region 76 such that ends 78 and 80 of the fiberare in spaced axial alignment within the laminated structure. Anaperture 82 is provided through top surface 84 of the laminatedstructure, and occlusive material 86 may be selectively placed in theaperture to prevent light entering as illustrated at 88 from exiting asillustrated at 90, thereby to provide means for altering theinformational state of the optical path defined by optical fiber 70.Note that with gaps or separations on the order of four mils wide andfibers having a four mil diameter there is sufficient opticaltransmission between the separated axially aligned faces of the fiber,as discussed below. Thus, a sufficient amount of light is transmittedacross the gap, absent occlusive material therein. Moreover, the fibermay be separated by merely drilling or punching through top surface 84and through the optical fiber 70, thereby simultaneously creating boththe aperture and separating the fiber into sections. Alternatively, asshown in FIG. 6B, two fibers 81 and 83 are located side-by-side, withthe ends 85 and 87 of both fibers exposed at an aperture 89. When noocclusive material is deposited in this aperture, narrow bandwidth lightfrom fiber 81 is scattered by the walls of aperture 89 and is reflectedback through fiber 83. The deposition of occlusive material within theaperture blocks this back-reflection of light through fiber 83.

The FIG. 6 embodiments provide simple physical configurations for anembedded fiber paper which is utilized with an active system in which alight source is positioned at one end of a fiber and a detector at theend of the same or another fiber. The systems illustrated in FIGS. 6Aand FIG. 6B do not, therefore, depend on ambient light and result in anenhanced signal and simplified signal detection for the entire system.

Applications

Referring to FIGS. 7A, 7B, and 7C, what is illustrated is a variety ofdifferent applications for the subject input/output device. Referring toFIG. 7A, a catalog sheet 92 may be provided with a series of entry ports94 adjacent written material generally indicated at 96. Moreover, a partnumber, price-quantity matrix 98 may be provided at the bottom of acatalog sheet, with entry ports as illustrated. Note that the user isrelieved of error-prone detail such as recording the part number orprice, since that information can be retrieved from knowledge of whichapertures have been marked. Thus, the marking of the catalog sheet by apencil 100 provides all of the necessary information, such that when thecatalog is connected by a fiber optic cable 102 to a decoding unit 104,the information encoded in the catalog sheet may be read out anddisplayed at 106 or provided to a modem 108 for direct transmission to amanufacturer.

As illustrated in FIG. 7B, the subject input/output device may be in thenature of a game in which a game card 110 is provided with scratch-offindicia 112. The card is provided with appropriate entry ports for theoptical fibers underneath the indicia. Only selected cards will haveoptical ends at the required scratch-off points such that only whenthese cards have these entry ports exposed to ambient light will itindicate that the user of the card has won. The card may be providedwith a display area 114 which provides the player with a visualrepresentation of the fact that the player has won when selectedentry/exit ports are appropiately driven. Of course many types of gamesmay be played in this manner with a connect-the-dots game being shown at116. As in the case of the catalog sheet, the game card may be coupledvia a fiber optic link 118 to any type of processing system either inthe vicinity of the card or at a remote location.

As illustrated in FIG. 7C, a textbook 120 may be provided not only withentry ports generally at 122, but also with a display such asillustrated at 124, with the book being coupled at its binding via aconnector generally indicated at 126 to a local processing unit 128 by afiber optic cable 130. Processing unit 128 may include light sources anddetectors as well as decoding and encoding circuitry. This unit may beaugmented by any type of auxiliary processing unit 132, which mayinclude cassettes, microprocessors, a modem for telephone linkage to aremote computer, and the like. The fiber optic page in book formatallows the inexpensive medium of print to be combined with theadvantages of computer-driven feedback to the user. In the process, theuser is permitted to exercise a broad range of computer-readable,graphic actions, instead of being restricted to button-poking orknob-turning.

Use Of Multiple Port Fibers

Referring now to FIG. 8, an embodiment is illustrated in which opticalfibers 140 are associated one each with a single entry/exit port 142provided through a page 144 of laminated structure 146. This figureillustrates a two port approach, with the term "two port" referring tothe fact that a single fiber has two termination points and thatinformation transfer occurs only between these two points. Note that inthis embodiment each fiber corresponds uniquely to a point on the pageso that the points which have been marked are readily determined bywhich fibers have their outputs blocked.

Referring to FIG. 9, a multi-port configuration is illustrated in whicha carrier fiber 150 has coupled to it a large number of fibers 154 whichare associated one each with an entry/exit port 156. The purpose of themulti-port approach is to reduce the number of fibers leaving a pagewithout reducing the number of points capable of being sensed. In theapproach illustrated in FIG. 9, transmission paths are successivelycombined. Physically, there are a variety of coupling techniques forcombining transmission paths available in the prior art. One example isthe biconical tapered and fused coupler of FIG. 10 in which light 158from an entry/exit port is coupled to carrier fiber 150 by virtue of thetwisting and fusing of the fibers as illustrated, it being a property ofthe coupling that light 158 will be coupled into fiber 150. Splices ofthe type described in FIG. 10 are described in an article by J. D.Dalgleish, entitled "Splicers, Connectors, and Power Couplers for Fieldand Office Use", Proceedings of the IEEE Vol 68, No. 10 October, 1980,pp. 1229-30, and also in Mitre Corporation's "Designer's Guide to FiberOptics" by Kleekamp and Metcalf.

Using ambient light and the multi-port approach of FIG. 9, positioninformation is not immediately available because a number of individualfibers are fused to a single carrier fiber. That is, without suitableencoding to identify an individual fiber, it is impossible to decode thelight output of the carrier fiber, so as to determine the positions ofthe marks on the page. Position information can be encoded or fibersidentified by a variety of means including spectral techniques. Forexample, optical filters with non-overlapping spectral passbands can bepositioned at the apertures by providing translucent films 157 or bydoping the ends of the fibers. In this embodiment, the spectral contentof the output signal unambiguously indicates which apertures have beenmarked.

Multiport Fibers And Active Light Sources

Referring now to FIG. 11, a multi-port approach different from thatillustrated in FIG. 9, utilizes an LED based strategy without requiringan entire fiber to be dedicated to a single aperture or position on thepage (n fibers for n positions). In particular, with an orthogonalmatrix, position information corresponding to n² points on the page isprovided by only 2n fibers. The primary features of the design are thatn fibers are used as light emitters and n fibers are used as lightdetectors. Suitable strobing or sequencing of light emission and lightdetection is capable of transforming the input marks on the paper intothe desired optical signals so as to unambiguously specify which pointshave been marked. Let X_(l) through X_(n) denote vertical fibers(columns) and Y₁ through Y_(n) denote horizontal fibers (rows). Assumemeans for coupling a row to a column at a particular crossover point,which coupling will be described hereinafter, then a strobing system forthe subject matrix might require that the fibers X₁ through X_(n) bestrobed sequentially, with LEDS associated one each with a fiber. Duringthe time interval that fiber X_(i) is being strobed with light, fibersY₁ through Y_(n) are sensed for the presence or absence of a lightsignal. Assuming point X_(i), Y_(j) has been marked, this state will bedetected via the absence of light on fiber Y_(j) as a result of the X, Yconnection pattern which will not be described.

At each X-Y intersection or crosspoint, a twisted and fused fibercoupler is provided as illustrated at 159, such that the fiber runs froma column to a row in the vicinity of a predetermined crossover point.This fiber is provided with a separation or gap immediately beneath anaperture in the surface of the laminated paper which operates in themanner described in connection with FIG. 11, such that is no occlusivematerial is placed in the aperture, here illustrated at 160, then lightwill be transmitted from, for instance, column X₁ to row Y_(n-1).Alternatively, if occlusive material is placed in aperture 160, therewill be no connection at the indicated crosspoint.

Light Attenuation Across a Gap

Referring to FIG. 12, a two-port approach is illustrated in which an LED161 is placed at one end 162 of a fiber 164 which is embedded in a sheet166. Fiber 164 is split apart along its length at, for instance, 188which is directly beneath an aperture 170 in sheet 166. The attenuationof light between the separated ends is a function of end separation andfiber core diameter, as well as the numerical aperture, with significantend separation being feasible without unduly large attenuation. Thuseven with the split, the fiber provides an adequate transmission pathfor light. The relationship of light loss to separation and fiberdiameter is illustrated in FIG. 14 for the parameters illustrated inFIG. 13, in which "Δ" indicates separation and "D" indicates diameter ofthe fiber, for numerical apertures of 0.5 and 0.15. It will beappreciated from inspection of FIG. 14 that the lower the numericalaperture, the lower the loss. As expected, the lower the ratio ofseparation to fiber diameter, the lower the loss.

Connector Structures

While the subject invention is envisioned as being utilized with a fiberbundle extending out from the edge of each page, referring to FIG. 15,it may be convenient to provide a connector 200 which overlies a pageedge 202 such that a page 204 is sandwiched in a channel 206 inconnector housing 208. Within the housing is embedded an array ofoptical fibers 210 which, when the connector is slipped over the page,are in optical alignment with fibers 212 embedded in the page. This typeof connector is useful in providing an optical link between theinput/output device and processing apparatus. It will be appreciatedthat the alignment of the fibers embedded in the housing with the fibersembedded in the page may be accomplished by locator pins or detents, asshown in FIG. 16, in which a page 220 may be provided with a reinforcingstrip 222 having locator detents 224 formed integrally therewith.Connector 200 is provided with corresponding detent receiving apertures226 such that when the connector is slipped over edge 202, its locationrelative to the fibers in the paper is established by "feel".

Light Pen Embodiments

Embedded optic fiber paper can be used in conjunction with a lightdetecting or light emitting pen. For instance, as illustrated in FIG.17, an embedded optic-fiber page 234 may be used with a light pendetector 230 so as to determine the position of entry/exit ports 232being pointed at by the pen. Entry/exit ports 232 are linked via opticalfibers 236 to a light emitting diode driver 238 which is strobed via astrobing unit 240 in response to timing signals from a timing unit 242,the output of which is also coupled to a decode unit 244. The output oflight pen detector 230 is also coupled to decode unit 244. By strobingthe fibers in a controlled timing sequence, a "hit" detected by the pencan be converted into position information. Spurious hits are avoided byswitching on the pen via a contact switch (not shown) only whenpositioned over a selected aperture. The actual placing of a mark isunnecessary in this mode of operation, but may be included for theuser's later reference.

Alternatively, and referring to FIG. 18, a light emitting pen can beused with fiber optic paper that is connected to a detector array. Inthis embodiment, a light emitting pen 250 is positioned over one of theentry/exit ports 252 in an embedded fiber paper 254, with the portsbeing connected via fibers 256 to a detector array 260. The output ofthe detector array is coupled to a decode unit 262 which identifies theentry/exit port at which the light emitting pen is located and thusdecodes the position of the pen. In operation, the pen emits light of aparticular bandwidth and intensity level which is directed into aselected aperture when triggered by a contact switch (not shown). Thelight is transmitted to the detector array through the underlying fiber,thereby enabling the selected aperture to be identifiedphotoelectrically. It will be appreciated that decode unit 262, in oneform, records the presence of a light intensity greater than apredetermined threshold.

Having above indicated a preferred embodiment of the present invention,it will occur to those skilled in the art that modifications andalternatives can be practiced within the spirit of the invention. It isaccordingly intended to define the scope of the invention only asindicated in the following claims.

What is claimed is:
 1. An input/output device in the form of a pagehaving one or more optical fibers therein, said device being selectivelycodeable by an individual using the device, the one or more opticalfibers being capable of being switched, after manufacture, by saidindividual from one informational state to another, each of said fibershaving a normal light-transmissive state and a non-light-transmissivestate in which the selection of the informational state of an opticalfiber is selectively codeable in real time from a position readilyaccessible by the individual at a designated location on a surface ofthe page, the device comprising:a thin, planar sheet having opposedsurfaces, a plurality of edges, and one or more designations on one ofsaid surfaces at one or more predetermined locations; at least oneoptical fiber embedded in said thin sheet, said fiber being divided intotwo sections to provide two ends embedded in the sheet, said embeddedends having faces orthogonal to the longitudinal axis of said fiber, theembedded ends being spaced apart by an amount which permits lighttransmission therebetween such that light in one section of the fiber istransmitted to the other section of the fiber across an interfaceestablished by said embedded ends for establishing the normallight-transmissive state of said fiber; the designation-containingsurface of said sheet having at least one aperture therethroughassociated with a respective designation, said aperture extendingthrough said designation-containing surface to the space defined by thecorresponding spaced-apart ends, said embedded ends being disposedwithin said aperture; each section of said fiber extending within theplane of said thin sheet to an edge thereof; and means insertable fromsaid apertured surface through said aperture into the space defined bythe spaced-apart embedded ends for selectively changing the normallight-transmissive state of said fiber to the non-light-transmissivestate by occluding the space between said embedded ends, such that thestate of said optical fiber embedded in said thin planar sheet isreadily changeable from one state to the other from thedesignation-containing surface of said device after the manufacturethereof, thereby to permit real-time coding of said device by theindividual using said device.
 2. The input/output device of claim 1,wherein said page includes at least two sheets laminated together withsaid optical fiber embedded therebetween, one of said sheets formingsaid designation-containing surface and having said aperturetherethrough.
 3. The input/output device of claim 1 wherein said sheetcontains a plurality of said optical fibers embedded therein;thedesignation-containing surface of said sheet having a plurality ofapertures therethrough, the spaced-apart embedded ends of each of saidoptical fibers being disposed within a respective aperture.
 4. Theinput/output device of claim 1 wherein said means insertable from saidapertured surface includes means for selectively depositing occlusivematerial in said aperture.